1. Field of the Invention
This invention concerns pneumatic oscillators, especially but not exclusively for the operation of resuscitators and/or ventilators and like devices for inducing or assisting lung function in human patients.
2. Background Discussion
In general, such devices generate a train of pulses of breathable gas that is ducted to a patient, usually via a so-called patient valve and/or an oronasal mask or tracheal intubation device. The generation of the pulse train with pulses at the required intervals and with appropriate tidal flow characteristics requires some form of switching mechanism controlling the flow of breathable gas from a source to the pulse output. Simplicity, reliability and constancy of performance in service, and robustness are dominant criteria in the design of resuscitators or ventilators, especially those intended for use by emergency services such as ambulance crews, or for use in a domestic environment by non-specialist operators.